Safety fuel



Patented Aug. 22, 1944/ SAFETY FUEL Cecil L. Brown-Baton Rouge, Lat, as signor to Standard Oil Development Company, a combration of Delaware No Drawing.

1938, Serial Original application December 7,- No. 244,357, "now Patent No. 2,321,280, dated June 8, 1943.

Divided andtliis application July 22, 1942, Serial No. 451,941

9 Claims.

This application is a division ofoopending application Serial No. 244,357; filed December '7, 1938, now Patent No. 2,321,280,-dated June 8, 1943.

'The present invention is directed to fuels for air craft, known as safety fuels.

Safety fuels are characterized by a high flash point, a high octane number, good volatility and gum stability; For example, a good safety fuel should have a Tag closed cup flash point of 100 F. or more, an octane number of about 100, and a boiling range of about BOO-400 F. It should have also the other characteristics of good aviation gasolina such as a good gum stability and a good break down test.

, The desirability of using a safety fuel has long been apparent in the aviation industry. Thus far, however, the industry has not universally adopted any standard safety fuel, primarily because there has been no available source of supply of such fuels at a suitable price.

It has hitherto been proposed to produce safety fuels by several methods such as the destructive hydrogenation of selected distillates or crudes, the extraction with sulfur dioxide of certain distillates or crudes, and the catalytic cracking under selected conditions of such extracts. The

fuels produced by the first method are rather high priced due to they limited quantity of suitable raw materials. The fuels produced by the latter two methods have so low an initial octane number and so low a lead susceptibility that the amount of lead required to convert them into 100 octane fuels makes their cost well-nigh prohibitive.

- I have now found that fuels having satisfactory characteristics for safety fuels such as high ini- I tial octane number, high lead susceptibility and suitable boiling range can be produced from C4 iso-hydrocarbons. For example, the copolymerization of normal and isobutylene yields a heavy hydrocarbon fraction which, when hydrogenated, boils between about 300 and 385 F.,,has a high flash point and a high octane number.

I have found thatby cutting the mixture of hydrocarbons produced by the' reaction between an isoparaflin and an olefin, such as isobutane and normal or isobutylene, at about 300 F., it is possible to produce a heavy fraction having a boiling range of from about 300 to 400 F. which has a Tag closed cup flash in excess of 100 F., a high initial octane number, and a high lead susceptibility. A particularly desirable safety allrylation product with hydrogenatedtri-isobutylenes boiling between about 330 and 380 n, with the latter constituting from 10 to of the blend. I

The basic materials for the safty fuels of the present invention are available in large quanti-' ties and the methods by which they are converted into the desired safety fuels are not costly. For example practically all refinery gases resulting from cracking processes" of various types con tain substantial percentages of isobutylene and normal butylene which can be caused to copolymerize by being contacted with sulfuric acid of a strength ranging from to" at a temperature between about 175- and ,250 F. This process is usually conducted with a view of producing dimer, and to this end it may be desirable to recycle trimer to the reaction chamber. As the result of the present invention, this procincreased. i

There are large reservoirs of isobutane which can be utilized as sources of raw material for the second embodiment of the present invention. The reaction between isobutane and the oleflns of refinery gases proceeds with case at normal room temperatures in the presence of concentrated sulfuric acid. This reaction, which yields a product containing Cs+ hydrocarbons, can be made to yield substantial amounts ,of a product boiling within the safety fuel range by recycling Cs-Ci hydrocarbons tothe reaction zone.

The'fuels of the present invention se have an octane number of 100. The co-polymer of isobutylene and normal butylenes, when hydrogenated, has an octane number of about which can be brought to 99.5 with 3 cc. of tetraethyl lead per gallon. Likewise, the highboiling alkylation fraction, especially when blended fuel, according to the present invention, is a blend of the hat mentioned heavy fraction of with about 40% of hydrogenated triisobutylene, has a clear octane number of about 90 which can be raised to with 3 cc. of tetraethy'l lead per gallon.

Ifhe safety fuel of the present invention is preferably composed entirely of the reaction product of an lac-C4 hydrocarbon with a diflerent C4 hydrocarbon. It may be mentioned, however, that, when the fuel is an alkylation product, it may be produced from isopent'ane or isohexane as wen as from isobutane. Likewise, oleflns other than the 'butylenes may be employ In any case, the

fuel, as previously mentioned," aycontain subdo not per ene.

.ed aromatics boiling between 300 and 400 F.

, ployed.

stantial quantities, of hydrogenated triisobutyl- Other suitable blending agents are alkylat- Typical examples of such alkylated aromatics are ethyl benzene, propyl benzene, isopropyl benzene, methyl benzene, o, m, p, trimethyl benzene, 1, 2, 3, trimethyl benzene 1, 2, 4, trimethyl benzene, 1, 3, 5, secondary butyl benzene, isobutyl benzene, tertiary butyl benzene, and methyl isopropyl benzene, p.

Alternatively, a fraction boiling between 300 and 400 F. of the product resulting from the alkylation of aromatics with olefins may be em- The characteristics of typical examples of aviation are given in the following table. Fuel A of this table was prepared by reacting isobutylme and normal butylene in the presence of sulfuric acid of a strength of about 70% at a temperature of 170 F., recovering from the product a fraction boiling above 300 F. and hydrogenating this fraction by contacting it with a catalyst composed of M003, ZnO and 'MgO at a temperature of 500-600 F. and under a pressure of 3000 pounds per square inch in the presence of a large hydrogenated triisobutylene boiling between 330 and 358 F., the latter constituting 40% of the blend. 5

Fuel A Fuel 13 Fuel 0 55. 8 55. 8 +26 +27 182 189 0. 02 0.008 Passes Passes Passes Passe 3. 6 3. 8 1 2 Bromine No 3 1 2 Flash, Tag closed cup 103 104 Reid vapor pressure Below l# Below 1# Below 1;? Army octane number 89. 4 77.0 1 85.3 ArmT gloctane number+3.0 cc. 99. 5 96. 4 100 304 323 328 319 336 336 324 341 340 336 351 347 345 357 352 352 363 355 302 373 364 384 393 385 98. 0 98. 0 98. 0 l. 0 l. 0 1.0

The nature and objects of .the present invention having thus been described, what is claimed.

as new and useful and is desired to be secured by Letters Patent is:

1. A safety fuel boiling substantially completely between about 300 F. and about 400 F., hav- I ing a flash point of at least 100- F. by the closed said mixture containing also suflicient anti-knock agent to raise its octane number to 100.

2. A safety fuel boiling substantially complete- .ly between about 300, F. and 400 F., having a flash point of at least 100 F. by the closed cup method, composed predominantly of a mixture of paraflinic reaction products of an isoparaflin and an olefin and compounds formed by hydr o-' genating the condensation product of normal and isobutylenes said product boiling within the above-stated range and said mixture containing suflicient anti-knock agent to raise its octane number to about 100.

3. A safety-fuel boiling substantially completely between about 300 F. and 400 F., having a 'flash point of at least 100 F. by the closed cupmethod, composed of a mixture of hydrogenated tri-butylenes said product boiling within the above-stated range and parafflnic reaction proding a flash point of at least 100 F. by the closed cup method, composed predominantly of a mixture of parafilnic reaction products of isopentane and an olefin and compounds formed by hydrogenating the normally liquid condensation products of C4 olefins said products boiling within the above-stated range, said mixture containing sufficient anti-knock agent to raise its octane number to about 100. r

6. A safety fuel boiling substantially complete 1y between about 300 F. and about 400 F., having a flash point of at least 100 F. by the closed cup method, composed predominantly of a mix- Y ture of parafiinic reaction products'of isopentane and an olefin and compounds formed by hypounds formed by hydrogenating the normally liquid condensation product 0104 olefins said product boiling within the above-stated range,

drogenating the normally liq'uid condensation products of isobutylene said products boiling within the above-stated range, said mixture containing suflicient anti-knock agent to raise its octane number to about 100.

7. A safety fuel boiling substantially completely between about 300 F. and about 400 F., hav-' ing a fiash point of at least F. by the closed cup method, composed predominantly of a mixture of parafllnic reaction products of isopentane and an olefin and compounds formed by hydrogenating triisobutylene, said mixture containing sufflcient anti-knock agent to raise its octane number to about 100. I

8. A safety fuel boiling substantially completely between about 300 and 400 F.', having a flash point of at least 100 F. by the closed cup method, composed of hydrogenated triisobutylene and the parafllnic compounds formed by thereaction between isobutane and a C4 olefin, and containing sufllcient anti-knock agent to bring its octane number to about 100.

9. A safety fuel boiling substantially completely between about 300 and 400 F., having a flash point of at least 100 F. by the closed cup method, composed of hydrogenated triisobutylene and paraflinic compounds formed by the reaction between isobutane and isobutylene, and containing suflicient antiknock agent to bring its octane numbersto about 100.

cm L. BaowN. 

